Multi stage filter design

[ACEINC]

I have a 25'x50' inground pool. It is about 56,000 gallons and located in S. Florida. The pump and filter needs to be replaced. The pump is rusted out, filter is split.

The existing pump is a 2.5 HP Hayward single speed. The filter is a 72 Sq. Ft. DE filter. I like the clarity that the DE filter gives. However the maintenance is a PITA.

My thought was to use two filters, a sand filter, followed by a DE filter in series. My thought is that this will allow the easier to maintain sand filter to catch the big stuff, and the DE filter will catch the smaller stuff. I was thinking it would tend to protect the DE filter from over pressure, as the sand filter will clog first.

My questions concern the advisability of this approach, and what pump(s) and filters would work in this environment considering the volume of water that needs to be exchanged. I am looking at using multi-speed pumps for efficiency's sake.

Paul